1. Field of the Invention
The present invention relates to a coupling apparatus for joining two discrete sections of asbestos-cement pipe in fluid communication, and to a method for repairing asbestos-cement pipe, the coupling apparatus, when properly mounted on an asbestos-cement pipe having utility in joining a replacement pipe in fluid communication with the individual discrete sections of asbestos-cement pipe, the coupling apparatus further making possible repair and replacement of a damaged section of asbestos-cement pipe with increased speed, safety, and dependability not possible heretofore.
2. Description of the Prior Art
Asbestos-cement pipe was first introduced into the U.S. in 1929. By 1974, an estimated 200,000 miles of asbestos cement pipe had been installed and recent estimates indicate that this figure may now be roughly 400,000 miles. Asbestos-cement pipe has been manufactured in various sizes from as small as 4 inches in diameter through as large 39 inches. It should be understood that asbestos-cement pipe has been primarily employed for water or fluid transmission in municipal, industrial, and agricultural applications.
Recent studies have linked the ingestion of asbestos fibers with lung and gastrointestinal cancer in human beings. In response to these studies the Environmental Protection Agency has proposed a ban on all asbestos products, including asbestos-cement pipe. Further, the greater availability, and cost effectiveness of polyvinylchloride, (PVC) pipe, as well as a general reduction in large scale pipeline water projects throughout the United States has led to a dramatic reduction in the demand for asbestos-cement pipe. With a lack of consumer demand for such a product, and with the assorted environmental regulations which may restrict the utilization of such a product, manufacturers of asbestos-cement pipe products have correspondingly reduced their production levels, as well as limited the numbers and types and sizes of related asbestos-cement products produced. For example, asbestos-cement pipe in diameters larger than 21 inches is no longer commercially available. Further, asbestos-cement pipe in sizes of 14 through 21 inches are only manufactured by one company in the United States, and then in that instance, only on a special order basis which requires some five to eight months for manufacture. Further, other manufacturers of asbestos-cement pipe have decided to completely abandon manufacturing these products.
With nearly 400,000 miles of asbestos-cement pipe in use, repair of such pipelines becomes a serious problem. In addition, and compounding the repair problem is that prior to 1971, dimensional standards in the asbestos-cement pipe industry did not exist. Therefore, different brands of asbestos-cement pipe could not necessarily be utilized together, nor could post 1971 asbestos-cement pipe necessarily be utilized in combination with 1971 and earlier dimensioned asbestos-cement pipe.
Repair kits for repairing damaged sections of asbestos-cement pipe have been commercially available. Such kits have been manufactured by the CertainTeed Corporation, of Riverside, CA, CAPCO Pipe Co. of Birmingham AL; and the Ershigs Corporation of Bellingham, WA.
While these prior art asbestos-cement pipe repair kits have operated with varying degrees of success, they commonly possess shortcomings which have detracted from their usefulness. For example, the asbestos-cement pipe repair kit marketed by CertainTeed Corporation includes a multiplicity of various parts and which are operable, in various combinations, to close assorted distances between adjoining sections of asbestos-cement pipe. These closure distances are in a range from zero to 13 feet. The repair kit provided by Certain Teed Corporation includes elements which are manufactured from asbestos-cement. With respect to the asbestos-cement pipe repair kit manufactured by Ershigs Corporation, the components of this kit are manufactured from fiberglass. While fiberglass does not present an environmental hazard as serious as asbestos, it may be cost prohibitive. For example the Ershigs Repair kit is approximately four times the cost of a comparable asbestos-cement pipe repair kit. Further, the Ershigs Corporation appears to manufacture the only repair kit which is available to repair asbestos-cement pipes which have outside diameters greater than 21 inches.
Still other significant problems results from the prior art devises and practices. For example, and in the event that the closure distance between the adjoining sections of asbestos-cement pipe does not coincide with the repair kit as provided, than in that instance, repair of a damaged asbestos-cement pipe becomes more difficult. In these situations, a field cut and/or machining of the asbestos-cement pipe would be required. This field cut and/or machining usually produces a significant volume of asbestos dust which requires special safety procedures. The overall procedure is very time consuming and very costly. This procedure, of course, assumes that an asbestos-cement pipe repair kit is available.
Therefore, it has long been know that it would be desirable to have a coupling apparatus, and a method for repairing asbestos-cement pipe, and which has particular utility in coupling a replacement pipe in fluid communication with a pair of discrete asbestos-cement pipes, the coupling apparatus operable substantially to reduce the time needed to repair a damaged section of asbestos-cement pipe while simultaneously increasing the effectiveness and worker safety thereof, with the attend economic benefits to be derived from such effective repairs.